The chronic fungal disease kills 85 per cent of all ash trees affected and it is feared it could even wipe out the species in Europe. It was first identified in the UK in 2012.
National Trust staff will attempt to contain its spread by removing affected trees between the Midgehole car park and Gibson Mill.
However the felled timber will be recycled to create 'leaky dams' as part of the Slow the Flow flood prevention scheme in the Calder Valley.
Parts of the main track and other paths will be closed for 10 days at Hardcastle Crags to allow contractors to remove trees safely. The work, which is part of the National Trust’s 10-year woodland management plan, will see closures in place from November 8-12 and 15-19.
National Trust countryside manager Rosie Holdsworth, said, “It’s devastating to see so many of our ash trees suffering as a result of ash dieback. The trees become very brittle and hollow, so we are removing those that are close to paths and the main track to ensure public safety.”
“We’re also continuing our woodland management plan, which will help improve our woodland’s resilience to future disease and climate change. We understand that some people have concerns about felling trees, but our work has been carefully researched to ensure we deliver the best possible outcome for nature, climate resilience and reducing tree disease. The woodland management plan has been approved by the Forestry Commission and Calderdale Council.”
The woodland management plan focuses on slowing the flow of water, restoring habitats for nature and improving the woodland's resilience to climate change. The work involves removing selective trees to increase the light that reaches the woodland floor, meaning better conditions for smaller plants to grow, including bluebells. Piles of sticks and leaves will be left on the woodland floor to create a home for insects and birds. These also help to slow the flow of water during heavy rainfall and minimise flood risk to downstream communities like Hebden Bridge.
As part of the work, 4,000 new trees will be planted at Hardcastle Crags. These are native species which are better suited to the steep valley sides of the woodland, including rowan, oak, birch, hawthorn and blackthorn.
A footpath diversion will also be in place during the closure period, although the alternative paths are steep, narrow and uneven. The riverside (Mill Walk) will also have a diversion in place. The route from Clough Hole car park to Gibson Mill is unaffected.
Ms Holdsworth added: “We understand how frustrating it is for visitors who won’t be able to access all of the woodlands at this time. However public safety is paramount, and we want to ensure that the work can be carried out with minimal risk for our visitors. We would recommend parking at Clough Hole car park where possible or visiting us at a weekend when no closures will be in place. This work is taking place in one of our quietest times of year, before we get ready to welcome visitors back for the run up to Christmas.”